Re: Time axis problem

[Ansley Manke <ansley@xxxxxxxxxxxxx>]

Hi Barry,
Is your first data sets a climatology, i.e. a time axis with no
year, and you want to subtract it from the "future" data
to see the anomoly?

Do  a "show axis axisname" with the axisname being
the time axis of the first dataset (which you can get from
show grid tmax[d=1]).  If you do not see an m after the
number of points, then you need to put this data on a
climatological axis.

I think that the answer is probably in making sure the first
time axis is a modulo axis, and one easy way to do that
is to regrid it onto a standard climaological time axis.

yes? set data historic
yes? set data future
yes? set data climatological_axes      ! defines several standard axes
yes? cancel data climatological_axes

! choose a monthly time axis and put the variable from
! the first dataset onto it.

let tmax_clim = tmax[d=1,gt=month_reg]

let tmaxdiff = tmax[d=2] - tmax_clim


"Barry B. Baker" wrote:

> Hi all,
>
> I'm rather new to Ferret and have a problem that I'm sure is simple.  Could not find a solution in the FAQ or the thread that exactly fit.
>
> I am trying to subtract the following
>
> set data historic  (tmax i=1:84 j= 1:36, l = 1:12, t= 16-jan:16-dec)
> set data future (tmax i=1:84, j=1:36, l=1225:1236, t=31-jan-2099:31-dec-2099)
>
> let tmaxdiff = tmax[d=2] - tmax[d=1]
>
> The error message is: Ambigous coordinates on T axis
>
> I tried the following without success
> let tmaxdiff = tmax[d=2, gt=tcltmax[d=1]@asn] - tmax[d=1]
>
> Any help would be greatly appreciated.
>
> Cheers,
> Barry
>
>
>
>
>

--
Ansley Manke  Pacific Marine Environmental Laboratory  Seattle WA  (206)526-6246